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| Re: [GMCnet] Installing Rockwell Aluminum Manifold [message #148316 is a reply to message #148299] |
Mon, 31 October 2011 18:47   |
powerjon
Messages: 2446
Registered: January 2004
Karma: 5
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Senior Member |
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Not to say that the manifold is not at fault, but has the motor been
rebuilt? It appears that one or both of the heads could have been
milled. Drivers side head deck height appears less than the pass side
in picture 3. Are both heads the same ID code? Should be "J" heads
and should have casting number 411783. "The casting number is found
around the center exhaust side rocker arm cover bolt or among the
rockers on really early heads [pre-68]. Really late heads have #'s
like 4417 or such, they might be out closer to the top of the exhaust
port. This number is also found on each side of the lower middle valve
cover bolt, split into 3-n-3 on each side of that bolt," (from olds
tech site) JMHO!
JR Wright
GMC Great Laker MHC
GMC Eastern States
GMCMHI
78 Buskirk 30' Stretch
1975 Avion (Under Reconstruction)
Michigan
On Oct 31, 2011, at 5:27 PM, Jp Benson wrote:
>
>
> I recently purchased a Rockwell aluminum manifold from the Applied
> folks for my GMC motorhome. After test fitting the manifold I found
> there were rather large tapered gaps at the front and rear of the
> manifold where it mates to the block. Pics are posted at: http://www.gmcmhphotos.com/photos/showphoto.php?photo=41388&title=front-seal-clearance&cat=5943
> . The front view shows a tapered gap that grows to over 0.200" on
> one side. The manifold is snugged into position with 4 bolts and
> there are no side gaskets which means the final gap will be even
> larger. To complicate matters, the mating surfaces are offset by
> almost 3/16" in the front. If I push the manifold as far forward as
> the bolts will allow, the mis-match is still 1/8". I don't feel very
> confident (using any kind of gasket/seal) spanning a 0.200" gap with
> a such a narrow bonding surface. Rockwell posted a fit test showing
> a uniform gap of .070". http://www.gmcmhphotos.com/photos/showphoto.php?photo=22826&title=spaci
> ng-manifold-fit&cat=3738.
> Has anyone else seen this problem and how did they deal with it?
> _______________________________________________
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J.R. Wright
GMC GreatLaker
GMC Eastern States
GMCMI
78 30' Buskirk Stretch
75 Avion Under Reconstruction
Michigan
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| Re: Installing Rockwell Aluminum Manifold [message #148351 is a reply to message #148299] |
Tue, 01 November 2011 01:08 |
George Beckman
Messages: 1085
Registered: October 2008
Location: Colfax, CA
Karma: 11
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Senior Member |
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| Jp Benson wrote on Mon, 31 October 2011 14:27 |
I recently purchased a Rockwell aluminum manifold from the Applied folks for my GMC motorhome. After test fitting the manifold I found there were rather large tapered gaps at the front and rear of the manifold where it mates to the block. fit&cat=3738.[/url]
Has anyone else seen this problem and how did they deal with it?
|
I my Rockwell is on its 4th mount. One, in fairness was when the engine was rebuilt. I love the lightness and the way it looks.
I did not have the gap problem you show, but I did find this:
The "lips" on my Rockwell ports were thinner than the 455 original intake, meaning the mounting face area that goes against the head ports was smaller (thinner). I was told to put studs in the heads and hang the gasket on the studs. Won't work with mine. (on two engines) I ended up mounting the gasket on the manifold with The Rightstuff first. When it was centered on the manifold the bolt holes would were about 50% off. I had to carve the bolt holes so the bolts could get to the heads. I used Mr. Gasket 404 (If memory serves) and I believe I have a seal this time.
I have used as much as 8 quarts of oil in about 450 miles because of the gap between the intake and the heads, at the bottom. So, you are right to be concerned. Also, at the ends, of course you have the danger of water leaking into the oil.
'74 Eleganza, SE, Howell + EBL
Best Wishes,
George
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| Re: Installing Rockwell Aluminum Manifold [message #148386 is a reply to message #148351] |
Tue, 01 November 2011 11:00 |
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WD0AFQ
Messages: 7111
Registered: November 2004
Location: Dexter, Mo.
Karma: 207
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Senior Member |
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| George Beckman wrote on Tue, 01 November 2011 01:08 |
| Jp Benson wrote on Mon, 31 October 2011 14:27 |
I recently purchased a Rockwell aluminum manifold from the Applied folks for my GMC motorhome. After test fitting the manifold I found there were rather large tapered gaps at the front and rear of the manifold where it mates to the block. fit&cat=3738.[/url]
Has anyone else seen this problem and how did they deal with it?
|
I my Rockwell is on its 4th mount. One, in fairness was when the engine was rebuilt. I love the lightness and the way it looks.
I did not have the gap problem you show, but I did find this:
The "lips" on my Rockwell ports were thinner than the 455 original intake, meaning the mounting face area that goes against the head ports was smaller (thinner). I was told to put studs in the heads and hang the gasket on the studs. Won't work with mine. (on two engines) I ended up mounting the gasket on the manifold with The Rightstuff first. When it was centered on the manifold the bolt holes would were about 50% off. I had to carve the bolt holes so the bolts could get to the heads. I used Mr. Gasket 404 (If memory serves) and I believe I have a seal this time.
I have used as much as 8 quarts of oil in about 450 miles because of the gap between the intake and the heads, at the bottom. So, you are right to be concerned. Also, at the ends, of course you have the danger of water leaking into the oil.
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DANG
3 In Stainless Exhaust Headers
One Ton All Discs/Reaction Arm
355 FD/Quad Bag/Alum Radiator Manny Tran/New eng.
Holley EFI/10 Tire Air Monitoring System
Solarized Coach/Upgraded Windows
Satelite TV/On Demand Hot Water/3Way Refer
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